Author: Chen, J.E.
Paper Title Page
MOPTY014 An Experimental Study of Higher-Order Modes Excited by High Repetition Rate Electron Beam in an SRF Cavity 965
 
  • Y. Gao, J.E. Chen, L.W. Feng, J.K. Hao, S. Huang, L. Lin, K.X. Liu, X. Luo, S.W. Quan, F. Wang, Zh.W. Wang
    PKU, Beijing, People's Republic of China
  
  Funding: National Natural Science Foundation of China (No. 11275014)
Higher-order modes (HOMs) excited by electron beam traversing a superconducting rf (SRF) cavity contain lots of information and can be used for intra-cavity electron beam diagnostics. Unlike single bunch, multiple bunches would excite HOMs with a much complicated spectrum. In this paper, we present our recent research on HOMs excited by a high repetition rate electron beam in an SRF cavity. Especially, we focus on the integer multiple frequency peaks in the HOM spectrum, which are determined by the nearest eigen HOM peaks. The experiments were carried out on the DC-SRF photoinjector, which was operated at MHz repetition rate. The results agree well with theoretic analysis. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY014  
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WEPWA027 Gas Flow Influence on Negative Hydrogen Ion Generation within the Microwave-Driven Negative Ion Source 2555
 
  • S.X. Peng, J.E. Chen, Z.Y. Guo, H.T. Ren, Y. Xu, A.L. Zhang, J.F. Zhang, T. Zhang, J. Zhao
    PKU, Beijing, People's Republic of China
  • J. Zhao
    State Key Laboratory of Nuclear Physics and Technology, Beijing, Haidian District, People's Republic of China
  
  H− ion was generated through two processes within a volume Cs- free source. The density of molecule hydrogen gas will impact the electron temperature within the primary discharge chamber that will influence the population of vibrationally excited H2*. Within the extraction region, the interaction between molecule hydrogen and H− ion will is cause the dissociation of negative ion. To better understand the gas flow influence on H− ion generation within a volume negative ion source, a new Cs-free volume microwave-driven H− source body with two gas inlets was developed at Peking University (PKU). Experiment on gas flow and gas pressure distribution within the plasma chamber was carried out with this source body. In the meantime a two dimensional (2D) model for gas flow was developed. Details will be presented in this paper.
[1] S.X. Peng, H.T. Ren, Y. Xu, T. Zhang, etc., CW/Pulsed H− Ion Beam Generation with PKU Cs-free 2.45 GHz Microwave Driven Ion Source. O5-06, NIBS 2014, Accepted for publication in AIP, 2014/11/04. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA027  
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WEPMN013 Development of DC-SRF Injector at Peking University 2944
 
  • J.K. Hao, J.E. Chen, P.L. Fan, L.W. Feng, S. Huang, L. Lin, K.X. Liu, S.W. Quan, F. Wang, Zh.W. Wang, X.D. Wen, H.M. Xie, K. Zhao, F. Zhu
    PKU, Beijing, People's Republic of China
  
  DC-SRF electron injector, which combines a DC Pierce gun and a 3.5 cell 1.3 GHz superconductor cavity in a cryomodule, has been developed at Peking University. Based on the improvements of beam line, LLRF system and 2K cryogenic system, stable operation of the DC-SRF injector has been carried out recently. Electron beams with 3.4 MeV energy and the currents of ~1mA in a macro-pulse mode was obtained. As the first application of this DC-SRF injector, THz radiation produced with a 10 period undulator was also detected. The description of the experiment process and results will be presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN013  
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